This study proposes a comparison of the relative and combined efficacy of a narcotic antagonist (naltrexone) and behavior therapy in the treatment of narcotic addiction. Sixty heroin addicts, aged 18-25, from Ventura County will be randomly assigned to one of three treatment conditions: 1) Narcotic antagonist (naltrexone) alone; 2) behavior therapy alone and 3) narcotic antagonist and behavior therapy. Each treatment group will be assessed on several measures: a) urine assays for presence of heroin and other drugs; b) therapy attendance; c) self- reported drug cravings; d) physiological response to videotapes of a person "shooting-up;" 3) job performance; f) assertion behavior (measured both by paper and pencil and role playing procedures; g) report of families and friends; and h) subjective measures of response to narcotic antagonists. Follow-up will range from a minimum of four months for some Ss to two years. In addition to the main question of comparative outcome across treatment conditions, several process issues will be addressed: a) an examination of the efficacy of assertion training with addicts; b) an examination of subjective reaction to antagonist induction compared to placebo; c) an examination of the efficacy of contingency contracting; d) an examination of electric shock and covert sensitization in the suppression of drug urges; e) a comparison of the effects of aversion therapy and extinction on drug cravings; and f) a comparison of the extinction of drug cravings between this project using narcotic antagonists and another Ventura County project using methadone.